We have been unable to replicate the reported effects on calcium channel activity using recombinant gp-120. Nevertheless, the chemokine receptors to which gp-120 binds are coupled to pertussis toxin sensitive G proteins that regulate potassium channels through protein phosphatases. We have demonstrated that potassium channels are stimulated by agents which trigger lymphocyte apoptosis. Similarly, we have shown that overexpressing such channels kills human cells in vitro; however, we have also isolated stable cell lines that express the cloned K channels but do not die. In those cells, channel activity is inhibited by an unknown regulatory mechanism that we have begun to investigate. - chemokines, lymphocytes, apoptosis, potassium channels